Long term evolution (LTE) based on 3rd generation partnership project (3GPP) technical specification (TS) release 8 is a promising next-generation mobile communication standard.
As disclosed in 3GPP TS 36.211 V8.7.0 (2009-05) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, a physical channel of the LTE can be classified into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
The 3GPP LTE supports both frequency division duplex (FDD) and time division duplex (TDD). In the FDD, uplink (UL) transmission and downlink (DL) transmission use different frequencies. In the TDD, UL transmission and DL transmission use the same frequency. A user equipment supporting full duplex-FDD can simultaneously perform UL transmission and DL reception at a specific time. A user equipment supporting half-duplex-FDD and TDD can perform UL transmission and DL reception at different times.
In the TDD of 3GPP LTE, a DL subframe and a UL subframe coexist in one radio frame. When locations of the DL subframe and the UL subframe are predefined in the radio frame, it is called a DL-UL configuration.
In general, a wireless communication system has been designed by considering that there is almost no change when a base station uses a specific DL-UL configuration. This is because normal communication may be difficult when a mismatch occurs in the DL-UL configuration between the user equipment and the base station.
However, with the diversification of a type of a required service and with the increase in traffic, the base station needs to change the DL-UL configuration in a more flexible manner.